A spot welding gun is a device that applies forces around 400 daN (1daN=10N) to sheet parts placed between the electrodes. A significant number of robotized welding applications make use of guns whose effective arm length is on average of 400 mm. Supplied currents are of 10–17 kA and require sections for laminated cores, gun arms and electrodes of 600–800 mm2.
In order to meet said designing needs, known welding guns are quite heavy. The average weight of known welding guns with an effective length of 400 mm, force supplied during welding of 400 daN and welding current of 16,000 A or above, is around 80–85 kg.
In the case of welding guns designed to be mounted onto the arm of an industrial robot, gun weight is a crucial point. The gun should be designed depending on robot strain chart defining the maximum weight to be applied onto the wrist according to the center of gravity of the welding gun, so as to ensure the possibility of handling the gun with high accelerations.
Reducing gun weight permits using robots whose strain chart is smaller of one or two sizes than currently used robots. Such size reduction results in significant cost reductions when purchasing a robot.